Air block?

[Dotski]

I have just fitted new bath taps as the hot had/has an intermittent flow. ( I thought I was an air block originally and so ran a hose from the kitchen to the bath hot and flushed it through....It worked fine for a day or so and then fell to about 50% flow. I then thought it was the tap valve, but because of the age of the taps I wasn't able to replace them....so new taps fitted) I've run the hot for a good three minutes with good flow, turned it off and on.... fine. Turned it of and on again.....50% loss! All other hot taps are fine.

Any ideas chaps?

 

[masona]

Is the hot water supply from the cylinder?

 

[Dotski]

Yes

 

[kevplumb]

check the tank is filling properly

the ballvalve might be stuck

 

[Dotski]

The tank's fine as are all the other hot taps

 

[ChrisR]

Still sounds like an air lock, you get half a pipe-full quickly then it reduces. Mains pressure hose time again. Only other likely cause would be a flake of scale stuck in there - same treatment!
From loft to floor below, 3/4 inch or 22mm pipes, you should be getting about 20 litres per min with a big ol tap.

 

[Dotski]

If it is air...would a check valve do the trick?

 

[ChrisR]

Not helpful at all! A check valve is a non-return valve, the sort of thing one might use to stop mains going up a gravity-fed pipe.
An air lock occupies space in the pipe, only allowing water to run underneath it.

 

[Dotski]

I understand the principle of the non return valve, in that its purpose is to stop back siphonage, but would that still not stop the flow of air? (I'm assuming that the air is feeding back through the tap)

 

[ChrisR]

No. The air is simply stuck in a high or horizontal run of pipe, and needs blasting out. Taps don't take air back up until you cut the supply off.

If there was another good way we'd have told you.......